1. Field of the Invention
The present invention relates to a subsea valve actuator apparatus for actuating a subsea valve.
More specifically, the present invention relates to a subsea valve actuator apparatus for actuating a subsea valve which includes a pressure compensator so that a pressure difference across a seal of the actuator apparatus is minimized.
2. Background Information
Subsea actuators are used under water to actuate valves situated on the seabed and elsewhere. At such depths, the water exerts considerable pressure on the actuator. The actuator includes a housing for the rotatable reception therein of a worm which is rotated from outside the housing. The worm intermeshes with gearing on a worm wheel such that as the worm is rotated several times, the worm wheel is rotated through part of a revolution. The worm wheel is connected to the valve so that rotation of the worm controls the position of the valve which is typically a quarter-turn valve such as a ball valve or butterfly valve, so that the valve is actuated between an opened and a closed disposition thereof.
However, the respective rotational shafts of the worm and worm wheel respectively must be sealed in order to seal and maintain lubricant within the housing. Accordingly, when the actuator is submerged, the seals are subjected to considerable pressure due to the water pressure outside the housing. The present invention provides means for equalizing the pressure of the lubricant within the housing to the water pressure outside the housing so that the seals are able to reliably maintain the lubricant within the housing.
Therefore, the primary feature of the present invention is the provision of a subsea valve actuator apparatus that overcomes the problems associated with the prior art actuators and which makes a significant contribution to the subsea valve actuator apparatus art.
Another feature of the present invention is the provision of a subsea valve actuator apparatus that maintains an equal pressure between lubricant within the housing of the actuator and the water pressure outside the housing so that the seals maintain lubricant within the housing.
A further feature of the present invention is the provision of a subsea valve actuator apparatus that reduces the possibility of leakage of lubricant from the actuator and subsequent contamination of the environment.
Other features and advantages of the present invention will be readily apparent to those skilled in the art by a consideration of the detailed description of a preferred embodiment of the present invention contained herein.